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 * Copyright (c) 2007, Geophysical Center RAS
 * Sergey Berezin, Dmitry Voitsekhovskiy
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﻿using System;

namespace VisualEsse.DataEngine
{
    /// <summary>
    /// IComplexSelector is the interface that enables the complex selection of the object,
    /// i.e. multi-step selection.
    /// </summary>
    public interface IComplexSelector
    {
        /// <summary>
        /// Gets the number of levels for selection.
        /// </summary>
        int Levels { get; }

        /// <summary>
        /// Returns the values to select at the specified level.
        /// </summary>
        /// <param name="level">The level of selection. The value at the last level (equal to Levels) is the selected object itself.</param>
        /// <param name="values">Values those were selected on previous levels.</param>
        /// <returns>Returns the values to select at the level.</returns>
        System.Collections.IEnumerable ValuesAtLevel(int level, object[] values);

        /// <summary>
        /// Returns the number of suggested values for the specified level.
        /// </summary>
        /// <param name="level">The level of selection.</param>
        /// <param name="values">Values those were selected on previous levels.</param>
        /// <returns>Returns the number of suggested values for the specified level.</returns>
        int GetNumberOfValuesAtLevel(int level, object[] values);

        object[] Find(object finalValue);
    }

    public static class ComplexSelectorUtils
    {
        public static object GetFirstEntry(IComplexSelector source)
        {
            return GetEntryForLevel(source, 0, new object[source.Levels]);
        }

        private static object GetEntryForLevel(IComplexSelector source, int level, object[] values)
        {
            object obj = null;
            foreach(object o in source.ValuesAtLevel(level, values))
            {
                obj = o;
                break;
            }

            if (level == source.Levels)
                return obj;

            values[level] = obj;
            return GetEntryForLevel(source, level + 1, values);
        }
    }
}
